Can i use x265 to compress a RAW to JPEG without losing quality

Started 2 months ago | Questions thread
knickerhawk Veteran Member • Posts: 6,412
Re: Can i use x265 to compress a RAW to JPEG without losing quality

MackMack wrote:

mclewis wrote:

JPG already can give you a compressed image that is visually indistinguishable to the raw original. You just need to save with a high enough quality, the highest is not generally needed as it will not look better for a much larger file size.

Whether or not the highest quality JPEG compression setting is needed to ensure that the viewer can't see any difference depends on a number of factors: image content, types of edits applied during raw (post)processing, viewing size, quality of the monitor/viewer. While it's true that for most situations, the highest quality (least compressed) JPEG option is likely to be overkill/unnecessary, you really should run your own tests on your own content having applied your own edits to confirm which level of compression is acceptable for your clients' review and sharing purposes.

Ok, but just want to confirm one thing that if I need a very large size print (a big 55in x 60in) wall poster from this high-quality JPG then does it will give image quality as if it would have taken form RAW ? If yes then it's good.

Again, the same considerations as noted above apply. The amount of compression may make some differences when printed or none at all, even at such a large size. No categorical statement can be made. For instance, even with minimal compression applied, very fine gradients such as commonly present in blue sky shots may be rendered a bit differently. The look of the noise in the sky will be slightly different (likely less attractive and more blotchy) with any JPEG compression applied. It will be extremely subtle but a print size that big may be enough to be noticeable by a critical viewer. (Type of print/paper used also factors in here.)

one more thing I want to confirm form you is that I believe that the sharpness for big size print depend on Magapixcel (number of photodiode on Image sensor along with the lens ability to resolve that much pixels)

So, which means If I am shooting RAW on 8MP camera and other with 24MP camera then after converting these RAW to JPG for big size print (55in x 60in) will definitely different and the image from 24MP camera RAW to JPG will be sharper then 8MP camera.

This is now touching on what should be a bigger concern for the OP. The optimal amount/type of adjustments for an image will vary depending on the type of output (print vs. monitor) and print/viewing size. Differences in the amount/type of sharpening is only one example (and will also vary by paper type when printing). Perhaps even more important is consideration of the optimal color space to be applied and targeted for these different output purposes. You're probably prepping your JPEGs for viewing with a non-color managed device. That means outputting them to sRGB. However, most printers can print colors well outside of the sRGB gamut. Thus, you really should prepare your renderings destined for print to a larger color space, not sRGB. How much of a difference these factors ultimately make will, once again, vary by image and editing applied and the critical expectations of the customer.

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